KH/pH creeping up / SOLVED - Floramax is the culprit

I had a tank that was dirt/gravel that remained more or less stable at a pH of about 6.8. It wound up being completely overrun by tubifex, so I decided to redo everything and try an inert substrate. Since then I've been having trouble with the pH and KH of the tank growing slowly until it reaches KH = 3-4 and pH = 7.6.

Just this week I broke down and bought Seachem's acid and alkaline buffers. The combination of the two should allow you to basically set your pH. Over the course of a couple of days I adjusted the tank's pH slowly to the point that I want it, 6.8, and then did a water change using the combination of the two buffers to buffer the incoming water to 6.8 as well. After the change, pH = 6.8, KH = 1. Next day, pH = 7.2, KH = 2. Today, pH = 7.6, KH = 3.

This is very frustrating, and it's destroyed several sets of bumblebee shrimp eggs/babies thus far. After getting everything settled I really don't want to redo the entire tank again, but that's what I'm looking at right now if I can't figure this out.

I use RO water and after preparing it for the tank (fertilized, warmed, stirred thoroughly) the pH is in the low 6's and the KH is less than 1. I had been adding small amounts of my well water so that the tank had a KH of 1 or so, but have stopped doing that since this problem began a month or two ago.

The floramax claims that it does not affect pH (which is why I bought it) and though I've looked around the net, I haven't been able to find anyone who has seen this problem. It's possible, I suppose, that I got the bad batch that includes limestone chips or something, but I don't know why that would be.

I've never heard of driftwood causing these sorts of problems, but there is a newer piece of wood in there as well, along with an old piece that has been in one or the other tank for a year or more now without causing problems.

I thought, briefly, that maybe the presence of snails was causing the increase, until I did the math and figured out that they would have completely dissolved several times over by now. Mostly included for the entertainment factor of the idea.

I've currently got some of the floramax sitting in a container with fresh RO to see what happens, but I won't know that until tomorrow. I suppose I can take out all of the driftwood as well (and the snails...)

Any suggestions about what might be causing the rise would be welcome. It's acting like I've got a chunk of coral in there.

Nothing like typing out a big long message then solving the problem yourself literally 2 minutes later.

FLORAMAX SUCKS. There are actually limestone chips in the stuff. I found one odd looking piece, took it out of the tank, put it in a cup with some vinegar, and the little bugger started fizzing. Now I get to redo the entire thing unless I can find and remove each of the little limestone chips in the substrate. I might try to, but then again I might just throw the whole mess in my garden.

Now that I have checked more thoroughly, there are a number of these chips in the substrate. They are spread evenly throughout it and since I haven't added anything other than substrate, wood, and large granite rocks to the tank on setting it up, they must have come with the Floramax. There is no way I'll be able to separate out these chips from the lava rock that appears to make up most of the substrate.

I'm currently testing some of the chips in a small batch of RO water to test conclusively whether they are the source of my problems, but there really doesn't seem to be much room for doubt here.

A complete rescape has been done; I used fluorite this time around. I kept some of the old substrate in a container with fresh RO. Starting pH = 6 (or possibly lower), starting KH = 0-1. I'll recheck in three or four days and update this. Additionally, after my rescape I mucked about with my water until I had it closer to where I want it. I'm at KH = 1 and pH = 6.5 right now. It's actually a bit lower than I'd like, but c'est la vie. I'll be rechecking that as well. I replaced everything except for the floramax, so if it doesn't change then I know for certain that it was floramax and nothing else that has been giving me headaches.

Three days later -
In the tank, rescaped with Fluorite, pH = 6.5, KH = 1.
In the sample container, with a small quantity of Floramax midnight black that contained 2 small white chips, pH = 7.8, KH = 4.

I contacted Caribsea and was advised that their 100% satisfaction guarantee would cover this, provided that I could produce a proof of purchase. I, not being a pack rat of pathologic proportions, don't have that. I wasn't seeking compensation anyway, just thought it was an amusing side note. In response to my comments about the product not performing as advertised, the excuse given was that it is a natural product. I'm not sure why they feel that producing a natural product (whatever that's supposed to mean) gives them the right to make false claims on their container, but there ya go.

In short, I had persistent problems with pH and KH rising, regardless of my attempts to stop them. After removing nearly everything from the tank (driftwood was the only non-substrate/livestock item left) I finally noticed white chips in the substrate. By chance there were none on the surface in the front half of the tank, though they were there when I dug for them a bit. I tested the chips, the tests indicated that they were carbonate minerals of some sort, and I rescaped with Fluorite. I threw out the old stuff except for a small sample which, after testing, showed the same behavior that I had been fighting in my tank for 2 months or so. I have not had the same problem in the tank since.

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